Radiation therapy is often indicated for dozens of types of cancer in the abdomen and pelvic region of both men and women. Targets often include organs with cancer involvement and lymph node chains. For example, in 2011, approximately 300,000 men will develop cancers which necessitate radiation treatment to the abdomen, retroperitoneal and pelvic areas. For men with prostate and anal cancer, radiation therapy is often primary and curative. For others with prostate cancer who are not surgical candidates, or who have bladder or anal cancers or sarcomas involving the pelvis, radiation therapy is standard treatment with either a curative or palliative intent. For women, numerous cancers involving the abdomen, retroperitoneal and pelvic organs can be treated both with curative and palliative intention.
The course of radiation treatment for such cancers usually continues for a minimum of three weeks up to as much as seven weeks of daily therapy. The radiation is intended to kill tumor cells and spare normal surrounding tissue. Treatment is often done with 3-dimensional conformation or in an intensity-modulated or intensity-graded fashion to deliver maximal dose to the intended target and minimal radiation to the normal surrounding tissue. A specialist physician (i.e., radiation oncologist) works in conjunction with a team of physicists, dosimetrists, and radiation-therapy-machine operators (“therapists”) to plan and deliver the radiation treatment.
Since multiple radiation treatment sessions are required, a reproducible set-up is necessary to ensure that the target site receives the intended cumulative dose of radiation while the surrounding normal tissue is spared. This frequently involves permanent tattoo placement on the patient's skin so that the patient is lined up without rotation and each treatment can be precisely reproduced from the treatment plan. The tattoos enable precise set-up via laser triangulation; the tattoos must therefore be visible at each treatment session so that they can be aligned with a light field projected by the treatment apparatus. Furthermore, the precise height and table position depends upon shining a light field on the patient's skin and matching measurements and parameters made during treatment planning. In this way, through tattoo alignment for patient position and light field visualization for table height and rotation, the exact position can be reproduced each treatment. In conjunction with IMRT and IGRT and the CT scan, precise treatment may be delivered. In order to ensure tattoo and light-field visualiztion, patients are therefore traditionally treated without clothing or coverage of their genitalia. This is a source of some (psychological) discomfort and an indignity for many patients.
While the target volume for radiation therapy is often deep within the pelvis, the skin of the perineum and external genitalia often receives some unavoidable radiation dose. It is well recognized that acute and late morbidity can be reduced with careful planning and by limiting the amount of unintended irradiation received by the sensitive skin of the perineum and external genitalia. Fractionated doses delivered over the course of weeks are often recommended; daily fractions of less than 2 Gy are typical.
The curvatures, folds and irregularities of the perineum, scrotum, and labia can often lead to higher than desirable skin dose. Variations up to 10% can be seen in the dose to the skin redundancy. Accurate radiation values at the skin-air interfaces are extremely difficult to predict even with CT planning. As a result, male patients can receive higher doses than desired to the skin of the abdomen, perineum and scrotum simply because of male anatomy and the traditional treatment of men in a supine position without clothing or gown/sheet covering. The same is true for women receiving treatment to the abdomen, pelvic, and retroperitoneal areas.
Furthermore, the dry and moist desquamation (i.e., raw, peeling areas of skin) that can develop in hotspots and in areas where tissue folds upon itself can necessitate treatment breaks until the skin recovers. These treatment breaks compromise the efficacy of the radiation in killing cancer cells.
The optimal radiation therapy outcomes are achieved when (a) precise radiation treatment parameters are followed, (b) reproducible set-up is established and (c) patients are able to complete the scheduled treatment prescription without treatment breaks from acute skin toxicity. Receiving the full cumulative dose reduces the patient's risk of developing a local recurrence of the cancer or metastatic spread of the disease.
The prior art has proposed a variety of ways to address these and other problems associated with radiation treatment. For example, there have been a number of proposals for minimizing the radiation exposure of healthy tissues surrounding the target (e.g., prostate, etc.).
U.S. Publ. Pat. Appl. 2002/0023652, for instance, discloses a system and method for measuring and correcting the position of a patient with respect to a radiation treatment apparatus. According to this reference, reference coordinates at various locations on a patient's body are measured and stored. Prior to treatment, the patient must be positioned so that the actual coordinates of these locations on the patient's body match the reference coordinates. To achieve this, the patient is placed on a treatment table. The patient is likely to be out of position relative to the reference coordinates. The process begins by correcting a patient's posture, which refers to the position of one or more of the patient's body parts relative to that patient's other body parts. This is done by repositioning the measured body locations of the patient to match the relative positioning of the reference coordinates. Once the posture has been corrected, the measured body locations will be correct with respect to the rest of the patient's body. But the absolute coordinates of the body positions might be incorrect with respect to the treatment machine. As long as the posture is correct, all body locations will be misaligned by the same offset when compared to the reference values. The patient's entire body is then shifted as a single unit to place the patient in the correct absolute coordinates that match the reference coordinates.
U.S. Pat. No. 7,438,685 discloses an apparatus and method for registration, guidance and targeting of external beam radiation therapy. According to this reference, real-time ultrasound imaging during planning and treatment is used to localize soft tissue treatment targets and is fused with radiographic or CT data for conformal treatment optimization. This fusion technique supposedly provides accurate localization of the prostate or other target volume in real time. With an unambiguous localization of the target tissue, the radiation field can be optimized to reduce the volume of normal tissue that is irradiated.
U.S. Publ. Pat. Appl. 2010/0237259 discloses a method and device for image-guided dynamic radiation treatment. According to this reference, high doses of radiation can be administered to prostrate while sparing surrounding healthy tissue using a collimation method and apparatus that sculpts the radiation borders. The system/approach incorporates radiation sources that use a “fan” geometry, a collimation apparatus, an integrated 3d imager and tissue-interface imaging system to locate and track critical boundaries in real time, a dynamic patient support system that is shared by the imager and irradiation system, and motorized shielding filters.
As previously noted, another issue related to radiation treatment is the fact that the patient is often naked during planning and treatment sessions. JP 2006225810 (A) addresses this problem with a radiation therapy garment. The garment includes openings (32) and (22) that can be covered with closures. These openings permit treatment personnel to establish alignment, such as by aligning laser beams with alignment tattoos (M2) and (M3) shown in FIG. 3. Furthermore, the patient can be treated at M1 with a treatment beam through larger opening (22). Although the openings must be open for alignment and treatment, the garment does provide the patient with a modicum of privacy. The garment is loose fitting and does not provide any functionality other than simply “coverage” of the patient.